Biological signal transduction refers to the transmission of stimulatory or inhibitory signals into and within a cell leading, often via a cascade of signal transmission events, to a biological response within the cell. Many signal transduction pathways and their biological responses have been studied. Defects in various components of signal transduction pathways have been found to account for a large number of diseases, including numerous forms of cancer, inflammatory disorders, metabolic disorders, vascular and neuronal diseases. These defects can often occur at the gene level, where DNA insertions, deletions or translocations can, for example, cause cells to proliferate uncontrollably in the case of some cancers.
Signal transduction is often mediated by certain proteins called kinases. Kinases can generally be classified into protein kinases and lipid kinases, and certain kinases exhibit dual specificities. Protein kinases are enzymes that catalyze the phosphorylation of other proteins and/or themselves (i.e., autophosphorylation) and can be generally classified based upon their substrate utilization, e.g.: tyrosine kinases which predominantly phosphorylate substrates on tyrosine residues (e.g., KIT, erb2, PDGF receptor, EGF receptor, VEGF receptor, src, and abl), serine/threonine kinases which predominantly phosphorylate substrates on serine and/or threonine residues (e.g., mTorC1, mTorC2, ATM, ATR, DNA-PK, Akt), and dual-specificity kinases which phosphorylate substrates on tyrosine, serine and/or threonine residues.
Epidermal growth factor receptor (EGFR) belongs to a family of receptor tyrosine kinases (RTKs) that include EGFR/ERBB1, HER2/ERBB2/NEU, HER3/ERBB3, and HER4/ERBB4. The binding of a ligand, such as epidermal growth factor (EGF), induces a conformational change in EGFR that facilitates receptor homo- or heterodimer formation, leading to activation of EGFR tyrosine kinase activity. Activated EGFR then phosphorylates its substrates, resulting in activation of multiple downstream pathways within the cell, including the PI3K-AKT-mTOR pathway, which is involved in cell survival, and the RAS-RAF-MEK-ERK pathway, which is involved in cell proliferation. (Chong et al. Nature Med. 2013; 19(11):1389-1400).
Approximately 10% of patients with NSCLC in the US (10,000 cases/year) and 35% in East Asia are reported to have tumor-associated EGFR mutations. (Lynch et al. N Engl J Med. 2004; 350(21):2129-39). The vast majority of NSCLC cases having an EGFR mutation do not also have a mutation in another oncogene (e.g., KRAS mutations, ALK rearrangements, etc.). EGFR mutations mostly occur within EGFR exons 18-21, which encode a portion of the EGFR kinase domain. EGFR mutations are usually heterozygous, with amplification of mutant allele copy number. Approximately 90% of these mutations are exon 19 deletions or exon 21 L858R point mutations. These mutations increase the kinase activity of EGFR, leading to hyperactivation of downstream pro-survival signaling pathways. (Pao et. al. Nat Rev Cancer 2010; 10:760-774).
Small deletions, insertions or point mutations in the EGFR kinase domain have been cataloged and described at length in the scientific literature. See e.g., Sharma, Nat Re. Cancer 2007; 7:169 (exon 19 mutations characterized by in-frame deletions of amino-acid 747 account for 45% of mutations, exon 21 mutations resulting in L858R substitutions account for 40-45% of mutations, and the remaining 10% of mutations involve exon 18 and 20); Sordella et al., Science 2004; 305:1163; and Mulloy et al., Cancer Res 2007; 67:2325. EGFR mutants also include those with a combination of two or more mutations, such as those described herein. For example, “DT” refers to a T790M gatekeeper point mutation in exon 20 and a five amino acid deletion in exon 19 (delE746_A750). Another common mutation combination is “LT” that includes the T790M gatekeeper point mutation and the L858R point mutation in exon 21.
EGFR exon 20 insertions reportedly comprise approximately 4-9.2% of all EGFR mutant lung tumors (Arcila et al. 2013; 12(2):220-9; Mitsudomi and Yatabe FEBS J. 2010; 277(2):301-8; Oxnard et al. J Thorac Oncol. 2013; 8(2):179-84). Most EGFR exon 20 insertions occur in the region encoding amino acids 767 through 774 of exon 20, within the loop that follows the C-helix of the kinase domain of EGFR (Yasuda et al. Lancet Oncol. 2012; 13(1):e23-31).
EGFR exon 20 insertion mutants, other than A763_Y764insFQEA, are associated in preclinical models, for the most part, with lower sensitivity to clinically achievable doses of the reversible EGFR TKIs, erlotinib (Tarceva) and gefitinib (Iressa), and of the irreversible EGFR TKIs neratinib, afatinib (Gilotrif), and dacomitinib (Engelman et al. Cancer Res. 2007; 67(24):11924-32; Li et al. Oncogene 2008:27(34):4702-11; Yasuda, et al. 2012; Yasuda et al. Sci Transl Med. 2013; 5(216):216ra177; Yuza et al. Cancer Biol Ther. 2007; 6(5):661-7), and of the mutant-selective covalent EGFR TKIs WZ4002 (Zhou et al. Nature 2009; 462(7276):1070-4) and CO-1686 (Walter et al. Cancer Discov 2013; 3(12):1404-15). The crystal structure of a representative TKI-insensitive mutant (D770_N771insNPG) revealed that it has an unaltered ATP-binding pocket and that, unlike EGFR sensitizing mutations, it activates EGFR without increasing its affinity for ATP (Yasuda et al. 2013).
Patients with tumors harboring EGFR exon 20 insertion mutations involving amino acids A767, S768, D770, P772 and H773 don't respond to gefitinib or erlotinib (Wu et al. Clin Cancer Res. 2008; 14(15):4877-82; Wu et al. Clin Cancer Res. 2011; 17(11):3812-21; Yasuda et al. 2012). In retrospective and prospective analyses of patients with NSCLCs harboring typical EGFR exon 20 insertions, most displayed progressive disease in the course of treatment with gefitinib or erlotinib or afatinib (Yasuda et al. 2012; Yasuda et al. 2013).
HER2 mutations are reportedly present in 2-4% of NSCLC (Buttitta et al. Int J Cancer 2006; 119:2586-2591; Shigematsu et al. Cancer Res 2005; 65:1642-6; Stephens et al. Nature 2004; 431:525-6). The most common mutation is an in-frame insertion within exon 20. In 83% of patients having HER2 associated NSCLC, a four amino acid YVMA insertion mutation occurs at codon 775 in exon 20 of HER2. (Arcila et al. Clin Cancer Res 2012; 18:4910-4918). HER2 mutations appear more common in “never smokers” (defined as less than 100 cigarettes in a patient's lifetime) with adenocarcinoma histology (Buttitta et al. 2006; Shigematsu et al. 2005; Stephens et al. 2004). However, HER2 mutations can also be found in other subsets of NSCLC, including in former and current smokers as well as in other histologies (Buttitta et al. 2006; Shigematsu et al. 2005; Stephens et al. 2004). The exon 20 insertion results in increased HER2 kinase activity and enhanced signaling through downstream pathways, resulting in increased survival, invasiveness, and tumorigenicity (Wang et al. Cancer Cell 2006; 10:25-38). Tumors harboring the HER2 YVMA mutation are largely resistant to known EGFR inhibitors. (Arcila et al. 2012).
Disclosed herein are compounds with inhibitory activity against a) mutant EGFR, such as EGFR having one or more exon 20 insertions, DT or LT, and b) mutant HER2 such as HER2 having a YVMA insertion mutation. Also disclosed are methods for preparing the compounds and pharmaceutical compositions containing them. In addition, methods are disclosed for inhibiting mutant EGFR bearing an exon 20 insertion mutation or bearing a, DT or LT mutation, and for inhibiting mutant HER2, as well as methods of treatment of disease mediated by any of those mutant EGFR or HER2 proteins, including cases that are resistant to known treatments of care